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Max wt? Displacement? What's the difference?

Discussion in 'Strippers, Stitch-n-Glue, and Other Wood Composite' started by Tnic, Apr 3, 2017.

  1. Tnic

    Tnic Paddlewon Canoobie

    That and pretty much every other NOOB question. :D

    I have very little paddle time in either canoes or kayaks, but I can say I DO like and I want to check a build and Allagash paddle off my bucket list.

    Soooo......

    I've been absorbing everything I can find on YT and will be ordering the bible of canoeing soon (i'm out of the country and its not offered in Kindle format).

    I've also been eyeballing a few kit & plan dot coms and I've seen some designs that I like buuuut.... One Mfgr gives their stats in Max Weight while another (like Noah boats) give displacement. Being the total noob that I am what does it mean?

    I want a canoe that will carry my wife and I (~350 lbs) and maybe 100 lbs of gear on most quiet lakes or rivers with very easy swift water flows so a total of about 450 lbs for a weekend camp out and hopefully a multi-day trip down the Allagash.

    I see a lot of folks on YT run 15'-16" boats (some of them with WAY too much crap), but then I look at say, the Prospector or Bob's Special on Noah and they show a displacement of 350 ish lbs. Then I look at Selway (S&G) and they show max wts of 500-700 lbs. What gives?

    I don't have sawdust in my blood, but I know which end of the saw to grab on to so I'm confident that I can so this.


    TIA
     
  2. Benson Gray

    Benson Gray Canoe History Enthusiast Staff Member

  3. OP
    OP
    Tnic

    Tnic Paddlewon Canoobie

    Thanks Benson, but I still don't get it.

    Noah Marine isn't even consistent between their stripper & S & G offerings. Their 15' Bob's is listed with 345 lbs Displacement while their S & G 15' Townsend has a Recommended on board wt of 150-800 lbs. Am I to understand the Bob's will only handle a load (including paddlers, gear, etc) of 345 lbs? Meanwhile the plywood offering will take on another 455 lbs?
     
  4. Benson Gray

    Benson Gray Canoe History Enthusiast Staff Member

    There is no simple and universal solution to this problem. I don't believe that any formula will ever tell you how much you can safely carry in every situation. I would encourage you to try out a number of different canoes to see which ones feel best to you. Many of the large Maine retailers like L. L. Bean (https://www.llbean.com/) and the Kittery Trading Post (https://www.kitterytradingpost.com/) have annual demonstration days when you can try out a broad variety of canoes from many manufacturers. Another option is to attend something like the WCHA's annual Assembly (http://www.wcha.org/annual-assembly/), the Maine Canoe Symposium (http://www.mainecanoesymposium.org/), a local WCHA chapter event (http://www.wcha.org/local-area-chapters/), or some other large gathering of canoes where you can try out a number of them. Then you can make a more informed decision by selecting a design that most closely matches the dimensions and shapes of the canoes that you are most comfortable with.

    Page 24 of the 1974 Old Town Canoe catalog stated, "Some regulating agencies have established formulas that limit the number of persons and/or total loading capacities of canoes. Old Town believes that a combination of canoeist's experience, type of canoe, and water-weather conditions, rather than arbitrary formulas, is the best guide in such matters." Your mileage may vary...

    Benson
     
    Last edited: Apr 3, 2017
  5. pklonowski

    pklonowski Unrepentant Canoeist

    Another option might be to call the various vendors, and ask them to clarify what exactly they mean. Especially if some (Noah) doesn't use the same format for the information, they should be able to explain what they really mean!
     
  6. OP
    OP
    Tnic

    Tnic Paddlewon Canoobie

    Thanks very much for all the expended neurons gentlemen.

    I did a little digging round and found some useful info on Bear Mt.


    Terms to look for when studying boat plans:

    Capacity: Safe working load

    Displacement: Weight necessary to sink the boat to the design waterline

    Weight to immerse: Number of pounds necessary to sink the hull each additional inch past the design waterline.
     
  7. Todd Bradshaw

    Todd Bradshaw Sailmaker

    As you have noticed, there is generally no "apples-to-apples" comparison going on between the manufacturers. "Weight" of a canoe denotes how much it weighs when you pick it up to portage it, or load it on the car. "Displacement" is, as mentioned, the amount needed to submerge it to its designed waterline. This amount is a combination of the hull weight, the passenger weight and the weight of any gear present. The designed waterline for most canoes is usually three or four inches above the bottom of the boat, but its exact height is up to the designer and there are no hard and fast rules for it. It is just the point where the designer figures the hull will sink down into the water during typical use. Displacement values aren't as useful on canoes as they are on big boats, as a canoe's displacement and the amount of submerged hull due to it can vary drastically depending on the exact passenger and gear load.

    There are also manufacturers who quote the capacity as a function of remaining freeboard. Basically, it is simply saying something like "This is how much weight the hull can hold and still have six inches of the canoe's sides clear of the water's surface amidships to keep waves out". Most of the high capacity values you'll see (Like 900 lbs., 1,100 lbs., etc.) are arrived at in this way. What they don't tell you is usually how totally awful the canoe's handling is if you actually load that much weight in it.

    There are, and always have been, plenty of canoes listed with very exaggerated capacity figures. Unless you're tripping with a whole camp kitchen full of of cast iron cookware you will probably never carry more than about half of the listed capacity, and similarly sized and shaped canoes from different manufacturers are going to generally have a pretty similar practical capacity.
     
  8. Jim Dodd

    Jim Dodd LOVES Wooden Canoes

    TIA

    For what you've described as your needs, I'd go with a 17' foot tandem with a 32/34" width
    the Bear Mountain Freedom 17 has received high marks.
    Myself, I'd build it stemless, and save the headache and extra work of building stems !

    Jim
     
  9. OP
    OP
    Tnic

    Tnic Paddlewon Canoobie

    @ Todd, Yeah, I've noticed the pretty much total lack of uniformity between the various Plans & Kits providers out there and even within the same provider. The one useful purpose I can see of knowing the displacement would be knowing what wt would give the best performance while paddling. I'd much rather have a usable knowledge of the optimal or working load capacity tho. The freeboard stat is actually more informative than displacement.

    I might pack ONE CI skillet for a weekend camp out at one site, but I wouldn't want (or need) more than 100 lbs of gear for a couple day trip and never that much if there's any portaging involved. Dehydrated/freeze dried vittles are the way to go. So, the max payload would rarely nudge 450 lbs.



    @ Jim, The Freedom looks like a really sweet boat. In fact I just finished watching BM's video workshop series where the class built one. The Prospector 16 is another one I like a lot. Those classic lines kinda draw me in and Noah has the plans on sale for $45 right now.

    Went thru your Nokomis build thread last night. SUWEET! We have a Nokomis HS in a nearby town.

    And another thought occurred to me last night. I was setting up for a kayak build a couple years ago. I designed a tandem 20' with kayak foundry. I have about 60 bf of rough cut EWC in the barn rafters at my folks place.
     

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